Avoiding the “capturing self strongly in this block is likely to lead to a retain cycle” message

Question

every time I have to use a global var or property inside a block like this:

self.save = ^(){
  if (isItSaving == NO) {
      [self saveMyFile];
  }
};
         


        

Answer 1

The problem only occurs when referencing self from within the block, explicitly or implicitly. There's no warning emitted when accessing global variables.

In your case you probably accessed a (boolean) ivar. Accessing the ivar implicitly uses self, that's why the compiler is warning you (correctly) about a retain cycle.

The common way to fix the retain cycle is:

typeof(self) __weak weakSelf = self;

self.save = ^() {
    typeof(weakSelf) __strong strongSelf = weakSelf;
    if (strongSelf != nil && ! strongSelf->isItSaving) {
        [strongSelf saveMyFile];
    }
};

... and, yes, that's a bit of an ugly part of blocks.